The diffuse infiltrating lymphocytosis syndrome (DILS) may be the most common rheumatic disease seen in HIV+ individuals. The presence of DILS may retard the progression of HIV infection. The aims of this study are to 1) determine the prevalence of DILS in a large HIV+ population, 2) better define the natural history of DILS by long-term followup, 3) by studies of HLA and other genetic markers better define those at risk for DILS and to determine the effect of the markers on DILS, 4) examine the response to corticosteroids in treating DILS.